RESUMEN
Ergot alkaloids, a class of mycotoxins associated with ergotism, act as agonists on serotonin (5HT) receptors, specifically 5HT2a, which mediate smooth muscle contraction and vasoconstriction. The objective of this study was to examine the impact of ergot alkaloid exposure during mid and late gestation on microscopic placental structure and vascular development. Ewes were fed endophyte-infected tall fescue seed containing ergot alkaloids (E+/E+, 1.77 mg ewe-1 d-1) or endophyte-free tall fescue seed (E-/E-, 0 mg ergot alkaloids) during both mid (d 35 to d 85) and late gestation (d 86 to d 133). On d 133 of gestation, a terminal surgery was performed and two placentomes of the type B morphology were collected for microscopic analyses. Amorphous connective tissue regions were larger (p < 0.0001) and more numerous (p = 0.025) in the placentome of ergot alkaloid exposed ewes. Staining showed no difference (p = 0.83) in the number of vessels present, but luminal area of maternal vasculature was 117% greater (p < 0.0001) in ergot alkaloid exposed ewes. Results showed that exposure to ergot alkaloids during gestation slowed maturation of the fetal villi as indicated by greater amorphous connective tissue regions, and altered size and shape of blood vessels to counteract reductions in blood flow caused by vasoconstriction.
Asunto(s)
Alcaloides de Claviceps , Festuca , Animales , Endófitos/fisiología , Alcaloides de Claviceps/farmacología , Femenino , Festuca/química , Placenta , Embarazo , Ovinos , Oveja DomésticaRESUMEN
Astyanax anai, a new species of characid fish, is described from the Sixaola River basin, eastern Costa Rica-western Panama, Central America. The new species can be distinguished from all other congeners by the following combination of characters: premaxillary teeth 4-5 at the inner series and 4-6 at the outer series; maxillary teeth tricuspid, 2-4; predorsal scale series irregular and incomplete, with an unscaled space behind tip of supraoccipital process and 12-14 scales; lateral line scales 34-39; humeral region with a conspicuous black and rounded to horizontally ovate spot and two diffuse brown and vertically elongate bars (the first through the rounded to horizontally ovate spot, the second 2-4 scales behind the first); body depth 36·6-42·3% of standard length (LS ); midlateral stripe formed by a series of 10-14 anteriorly-directed dermal herringbone, or chevron-shaped, marks, most apparent in juveniles and in preserved specimens, extending above the lateral line from the black humeral spot or just behind it (from the second vertical bar) to the caudal peduncle; scale rows from lateral line to base of first dorsal-fin ray 8-9; scale rows from lateral line to base of pelvic fin 7-8; pre-anal distance 53·9-61·9% of LS ; total anal-fin elements 29-33; caudal spot elongated, rhomboid or rectangular, with its anterior margin surpassing the middle of the caudal peduncle, usually reaching the anal-fin insertion, posteriorly covering 4-7 principal caudal-fin rays and not extending onto the ventral and dorsal margins of the caudal peduncle, covering 3-5 horizontal scale rows. In order to test the phylogenetic relationships of the new taxon in relation to the other North and Central American species of the genus, a new phylogenetic hypothesis based on a reanalysis of the morphological matrix by Schmitter-Soto (2016) is proposed. A key to the lower Central American (southern Nicaragua to eastern Panama) species of Astyanax is also provided.
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Characidae/anatomía & histología , Characidae/clasificación , Animales , Biodiversidad , Characiformes , Costa Rica , Femenino , Masculino , Panamá , Filogenia , RíosRESUMEN
BACKGROUND: We explored whether, the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) coronary and abdominal risk scores measured at 18 to 30 years of age and changes in these scores would more strongly predict coronary artery calcium (CAC) and abdominal aortic calcium (AAC) assessed 25 years later, than scores measured 25 years later. METHODS AND RESULTS: In the Coronary Artery Risk Development in Young Adults (CARDIA) study, 3008 participants had measurements of risk score components at 5-year intervals beginning at 18 to 30 years of age. CAC and AAC were assessed at 43 to 55 years of age. Odds ratios (ORs) for the presence and extent of CAC/AAC per/point higher score and c-statistics for predicting CAC/AAC were calculated. The prevalence of CAC was 28% and AAC was 53%. For each 1 point higher PDAY score, the odds of CAC were higher using baseline scores than year 25 scores (OR, 1.29; 95% confidence interval [CI], 1.25-1.33 versus OR, 1.12; 95% CI, 1.11-1.14). For AAC, ORs at years 0 and 25 were similar (OR, 1.29; 95% CI, 1.24-1.34 versus OR, 1.22; 95% CI, 1.19-1.26). C-statistic for CAC prediction was higher at year 0 than year 25 (0.731 versus 0.705) but similar at years 0 and 25 for AAC (0.665 versus 0.670). ORs for CAC were highest at baseline, and, for AAC, ORs were highest at year 10. Including change in PDAY scores with baseline scores improved prediction. CONCLUSIONS: Atherosclerosis risk and change in risk assessed in young adulthood years before subclinical atherosclerosis imaging provide strong prediction of future subclinical atherosclerosis. CAC and AAC reflect chronic risk exposure in addition to risk measured at the time of study.
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Enfermedades de la Aorta/epidemiología , Aterosclerosis/epidemiología , Calcinosis/epidemiología , Enfermedad Coronaria/epidemiología , Índice de Severidad de la Enfermedad , Adolescente , Adulto , Edad de Inicio , Aorta Abdominal , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Oportunidad Relativa , Pronóstico , Riesgo , Medición de Riesgo , Factores de Riesgo , Estados Unidos/epidemiología , Adulto JovenRESUMEN
AIM: The objective of the study was to compare (i) esthetic, (ii) clinical and (iii) patient-centered outcomes following immediate (Type 1) and early implant placement (Type 2). MATERIAL AND METHODS: Thirty-eight subjects needing a single extraction (premolar to premolar) were randomly allocated to Type 1 or Type 2 implant placement. Three months following permanent crown insertion, evaluation of (i) esthetic outcomes using soft tissue positions, and the pink and white esthetic scores (PES/WES), (ii) clinical performance using probing pocket depth (PPD), modified plaque index (mPI) and modified sulcus bleeding index (mSBI) around each implant and (iii) patient satisfaction by means of a questionnaire using a visual analogue scale (VAS) was performed. RESULTS: Thirty-two patients completed the 3-month follow-up examination (Type 1, n = 17; Type 2, n = 15) with a 100% implant survival rate. Type 1 implants lost 0.54 ± 0.18 mm of mid-facial soft tissue height, while Type 2 implants lost 0.47 ± 0.31 mm (P > 0.05). The papillae height on the mesial and distal was reduced about 1 mm following both procedures. The PES/WES following Type 1 implant placement amounted to 13.7 ± 0.6 and 12.5 ± 0.7 in the Type 2 group (P > 0.05). PPD, mPI and mSBI were low in both groups (P > 0.05). Patient-centered outcomes failed to demonstrate any statistical difference between the two cohorts. CONCLUSION: Three months following final crown delivery, there were no significant differences in esthetic, clinical and patient-centered outcomes following Type 1 and Type 2 implant placement. On the short term, one may achieve good optimal esthetic and clinical results irrespective of these two placement protocols. These results need to be confirmed on the long term.
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Coronas , Implantes Dentales de Diente Único , Prótesis Dental de Soporte Implantado , Estética Dental , Carga Inmediata del Implante Dental/métodos , Evaluación del Resultado de la Atención al Paciente , Índice de Placa Dental , Femenino , Humanos , Masculino , Persona de Mediana Edad , Índice Periodontal , Encuestas y Cuestionarios , Extracción Dental , Alveolo Dental/cirugía , Resultado del TratamientoRESUMEN
Hepatocellular carcinoma is increasingly important in the United States as the incidence rate rose over the last 30 years. C3HeB/FeJ mice serve as a unique model to study hepatocellular carcinoma tumorigenesis because they mimic human hepatocellular carcinoma with delayed onset, male gender bias, approximately 50% incidence, and susceptibility to tumorigenesis is mediated through multiple genetic loci. Because a human O(6)-methylguanine-DNA methyltransferase (hMGMT) transgene reduces spontaneous tumorigenesis in this model, we hypothesized that hMGMT would also protect from methylation-induced hepatocarcinogenesis. To test this hypothesis, wild-type and hMGMT transgenic C3HeB/FeJ male mice were treated with two monofunctional alkylating agents: diethylnitrosamine (DEN; 0.025 µmol/g body weight) on day 12 of life with evaluation for glucose-6-phosphatase-deficient (G6PD) foci at 16, 24, and 32 weeks or N-methyl-N-nitrosurea (MNU; 25 mg MNU/kg body weight) once monthly for 7 months starting at 3 months of age with evaluation for liver tumors at 12 to 15 months of age. No difference in abundance or size of G6PD foci was measured with DEN treatment. In contrast, it was unexpectedly found that MNU reduces liver tumor prevalence in wild-type and hMGMT transgenic mice despite increased tumor prevalence in other tissues. hMGMT and MNU protections were additive, suggesting that MNU protects through a different mechanism, perhaps through the cytotoxic N7-alkylguanine and N3-alkyladenine lesions which have low mutagenic potential compared with O(6)-alkylguanine lesions. Together, these results suggest that targeting the repair of cytotoxic lesions may be a good preventative for patients at high risk of developing hepatocellular carcinoma.
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Alquilantes/farmacología , Carcinoma Hepatocelular/prevención & control , Metilasas de Modificación del ADN/genética , Enzimas Reparadoras del ADN/genética , Dietilnitrosamina/farmacología , Neoplasias Hepáticas Experimentales/prevención & control , Metilnitrosourea/farmacología , Proteínas Supresoras de Tumor/genética , Animales , Apoptosis/efectos de los fármacos , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patología , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Hepatocitos/citología , Hepatocitos/efectos de los fármacos , Hepatocitos/metabolismo , Humanos , Técnicas para Inmunoenzimas , Neoplasias Hepáticas Experimentales/genética , Neoplasias Hepáticas Experimentales/patología , Masculino , Ratones , Ratones Endogámicos C3H , Ratones TransgénicosRESUMEN
Increased paternal age is associated with a greater risk of producing children with genetic disorders originating from de novo germline mutations. Mice mimic the human condition by displaying an age-associated increase in spontaneous mutant frequency in spermatogenic cells. The observed increase in mutant frequency appears to be associated with a decrease in the DNA repair protein, AP endonuclease 1 (APEX1) and Apex1 heterozygous mice display an accelerated paternal age effect as young adults. In this study, we directly tested if APEX1 over-expression in cell lines and transgenic mice could prevent increases in mutagenesis. Cell lines with ectopic expression of APEX1 had increased APEX1 activity and lower spontaneous and induced mutations in the lacI reporter gene relative to the control. Spermatogenic cells obtained from mice transgenic for human APEX1 displayed increased APEX1 activity, were protected from the age-dependent increase in spontaneous germline mutagenesis, and exhibited increased apoptosis in the spermatogonial cell population. These results directly indicate that increases in APEX1 level confer protection against the murine paternal age effect, thus highlighting the role of APEX1 in preserving reproductive health with increasing age and in protection against genotoxin-induced mutagenesis in somatic cells.
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ADN-(Sitio Apurínico o Apirimidínico) Liasa/genética , Mutagénesis/genética , Edad Paterna , Espermatogénesis/genética , Animales , Apoptosis/genética , Reparación del ADN/genética , ADN-(Sitio Apurínico o Apirimidínico) Liasa/biosíntesis , Regulación del Desarrollo de la Expresión Génica , Mutación de Línea Germinal , Humanos , Masculino , Ratones , Ratones Transgénicos , Espermatozoides/metabolismo , Espermatozoides/patologíaRESUMEN
Creating a learning environment that fosters student acquisition of self-assessment behaviors and skills is critically important in the education and training of health professionals. Self-assessment is a vital component of competent practice and lifelong learning. This article proposes applying a version of confidence scoring of multiple-choice questions as one avenue to address this crucial educational objective for students to be able to recognize and admit what they do not know. The confidence scoring algorithm assigns one point for a correct answer, deducts fractional points for an incorrect answer, but rewards students fractional points for leaving the question unanswered in admission that they are unsure of the correct answer. The magnitude of the reward relative to the deduction is selected such that the expected gain due to random guessing, even after elimination of all but one distractor, is never greater than the reward. Curricular implementation of this confidence scoring algorithm should motivate health professions students to develop self-assessment behaviors and enable them to acquire the skills necessary to critically evaluate the extent of their current knowledge throughout their professional careers. This is a professional development competency that is emphasized in the educational standards of the Commission on Dental Accreditation (CODA).
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Educación en Odontología , Evaluación Educacional/métodos , Autoevaluación (Psicología) , Estudiantes de Odontología , Logro , Algoritmos , Calibración , Educación Basada en Competencias , Humanos , Aprendizaje , Desarrollo de Programa , Autoimagen , Programas de AutoevaluaciónRESUMEN
BACKGROUND: The authors conducted a prospective cohort study to determine whether poor glycemic control is a contraindication to implant therapy in patients with type 2 diabetes. METHODS: The study sample consisted of 117 edentulous patients, each of whom received two mandibular implants, for a total of 234 implants. Implant-retained mandibular overdentures were loaded after a four-month healing period and followed up for an additional one year. The authors assessed implant survival and stability (by means of resonance frequency analysis) relative to glycated hemoglobin A1c (HbA1c) levels, with baseline levels up to 11.1 percent and levels as high as 13.3 percent over one year. RESULTS: Implant survival rates for 110 of 117 patients who were followed up for one year after loading were 99.0 percent, 98.9 percent and 100 percent, respectively, for patients who did not have diabetes (n = 47), those with well-controlled diabetes (n = 44) and those with poorly controlled diabetes (n = 19). The authors considered the seven patients lost to follow-up as having had failed implants; consequently, their conservative estimates of survival rates in the three groups were 93.0 percent, 92.6 percent and 95.0 percent (P = .6510). Two implants failed at four weeks, one in the nondiabetes group and the other in the well-controlled diabetes group. Delays in implant stabilization were related directly to poor glycemic control. CONCLUSIONS: The results of this study indicate that elevated HbA1c levels in patients with type 2 diabetes were not associated with altered implant survival one year after loading. However, alterations in early bone healing and implant stability were associated with hyperglycemia.
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Implantes Dentales , Prótesis Dental de Soporte Implantado , Fracaso de la Restauración Dental , Prótesis de Recubrimiento , Diabetes Mellitus Tipo 2/complicaciones , Hemoglobina Glucada/análisis , Adulto , Anciano , Anciano de 80 o más Años , Diabetes Mellitus Tipo 2/fisiopatología , Femenino , Humanos , Masculino , Mandíbula/cirugía , Persona de Mediana Edad , Estudios Prospectivos , Factores de Tiempo , Cicatrización de Heridas/fisiologíaRESUMEN
Children are vulnerable to environmental mutagens, and the developing germline could also be affected. However, little is known about whether exposure to environmental mutagens in childhood will result in increased germline mutations in subsequent adult life. In the present study, male transgenic lacI mice at different ages (7, 25 and 60 days old) were treated with a known environmental mutagen (benzo[a]pyrene, B[a]P) at different doses (0, 50, 200 or 300 mg/kg body weight). Mutant frequency was then determined in a meiotic cell type (pachytene spermatocyte), a post-meiotic cell type (round spermatid) and epididymal spermatozoa after at least one cycle of spermatogenesis. Our results show that 1) mice treated with B[a]P at 7 or 25 days old, both being pre-adult ages, had significantly increased mutant frequencies in all spermatogenic cell types tested when they were 60 days old; 2) spermatogenic cells from mice treated before puberty were more susceptible to B[a]P-associated mutagenesis compared to adult mice; and 3) unexpectedly, epididymal spermatozoa had the highest mutant frequency among the spermatogenic cell types tested. These data show that pre-adult exposure to B[a]P increases the male germline mutant frequency in young adulthood. The data demonstrate that exposure to environmental genotoxins at different life phases (e.g., pre-adult and adult) can have differential effects on reproductive health.
Asunto(s)
Benzo(a)pireno/toxicidad , Mutación de Línea Germinal , Mutágenos/toxicidad , Espermátides/efectos de los fármacos , Espermatocitos/efectos de los fármacos , Animales , Análisis Mutacional de ADN , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mutagénesis , Maduración SexualRESUMEN
How many incorrect response options (known as distractors) to use in multiple-choice questions has been the source of considerable debate in the assessment literature, especially relative to influence on the likelihood of students' guessing the correct answer. This study compared distractor use by second-year dental students in three successive oral and maxillofacial pathology classes that had three different examination question formats and scoring resulting in different levels of academic performance. One class was given all multiple-choice questions; the two other were given half multiple-choice questions, with and without formula scoring, and half un-cued short-answer questions. Use by at least 1 percent of the students was found to better identify functioning distractors than higher cutoffs. The average number of functioning distractors differed among the three classes and did not always correspond to differences in class scores. Increased numbers of functioning distractors were associated with higher question discrimination and greater question difficulty. Fewer functioning distractors fostered more effective student guessing and overestimation of academic achievement. Appropriate identification of functioning distractors is essential for improving examination quality and better estimating actual student knowledge through retrospective use of formula scoring, where the amount subtracted for incorrect answers is based on the harmonic mean number of functioning distractors.
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Educación en Odontología/normas , Evaluación Educacional/métodos , Patología Bucal/educación , Estudiantes de Odontología , Logro , Algoritmos , Evaluación Educacional/normas , Humanos , Aprendizaje , ProbabilidadRESUMEN
OBJECTIVES: Two-dimensional intraoral radiography is the most common tool for diagnosing root fractures (RFs). Cone beam CT (CBCT) is widely used to depict RFs in endodontically treated teeth. Beam hardening and other artefacts caused by gutta percha may result in an incorrect diagnosis when using CBCT only. A comparison of two CBCT machines with photostimulated phosphor (PSP) plate images enhanced with the equalization tool was carried out to detect RFs in endodontically treated teeth. METHODS: 66 roots were collected, decoronated and treated endodontically using the same technique with gutta percha. 33 of these roots were randomly selected and fractured; the 2 root fragments were glued together with 1 layer of methyl methacrylate and placed randomly in 8 prepared beef rib fragments. Large fields of view (FOVs) were acquired with one CBCT unit and small FOVs with the second CBCT unit. Periapical radiographs (using intraoral PSP plates) were also acquired. A contrast enhancement tool was used when evaluating the PSP plate images. RESULTS: Small FOV images had significantly higher accuracy (area under the receiver operating characteristic curve) and sensitivity in detecting RFs than PSP plates and large FOV images. The specificity of the enhanced PSP images was higher than, although not significantly higher than, the small FOV images and was significantly higher than the large FOV images. CONCLUSIONS: CBCT small FOVs should be acquired for depicting RFs of endodontically treated teeth. Images obtained using PSP plates had the lowest rate of false-positive results and their use can save the patient a radiation dose.
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Tomografía Computarizada de Haz Cónico/métodos , Radiografía de Mordida Lateral/instrumentación , Fracturas de los Dientes/diagnóstico por imagen , Raíz del Diente/lesiones , Diente no Vital/diagnóstico por imagen , Pantallas Intensificadoras de Rayos X , Área Bajo la Curva , Tomografía Computarizada de Haz Cónico/estadística & datos numéricos , Cavidad Pulpar/diagnóstico por imagen , Reacciones Falso Positivas , Gutapercha/uso terapéutico , Humanos , Variaciones Dependientes del Observador , Curva ROC , Dosis de Radiación , Intensificación de Imagen Radiográfica/instrumentación , Radiografía de Mordida Lateral/estadística & datos numéricos , Radiografía Dental Digital/métodos , Radiografía Dental Digital/estadística & datos numéricos , Materiales de Obturación del Conducto Radicular/uso terapéutico , Sensibilidad y Especificidad , Factores de TiempoRESUMEN
OBJECTIVES: The objective of this study was to compare the accuracy of root fracture detection in endodontically treated teeth using scans acquired with a 180° rotation motion compared with a 360° after which the patient exposure and number of basis images are doubled. METHODS: Sixty-six roots were collected and decoronated. All were treated endodontically. One-half of the roots were fractured, resulting in 2 root fragments which were then glued together. The roots were placed randomly in 8 prepared beef rib fragments. Five reviewers independently reviewed the scans twice, at different times. RESULTS: The specificity of the 360° scan was significantly higher than the 180° scan; doubling the basis images leads to a significant decrease in false-positive rates. Accuracy and sensitivity were not significantly different. CONCLUSIONS: Only the specificity is improved by the increased rotation and doubling of images. The accuracy and sensitivity are not improved.
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Tomografía Computarizada de Haz Cónico/estadística & datos numéricos , Procesamiento de Imagen Asistido por Computador/estadística & datos numéricos , Fracturas de los Dientes/diagnóstico por imagen , Raíz del Diente/lesiones , Diente no Vital/diagnóstico por imagen , Área Bajo la Curva , Reacciones Falso Positivas , Gutapercha/uso terapéutico , Humanos , Imagenología Tridimensional/estadística & datos numéricos , Variaciones Dependientes del Observador , Curva ROC , Materiales de Obturación del Conducto Radicular/uso terapéutico , Tratamiento del Conducto Radicular/métodos , Rotación , Sensibilidad y Especificidad , Raíz del Diente/diagnóstico por imagenRESUMEN
OBJECTIVES: Cone beam CT (CBCT) is used widely to depict root fracture (RF) in endodontically treated teeth. Beam hardening and other artefacts due to gutta-percha may increase the time of the diagnosis and result in an incorrect diagnosis. Two CBCT machines, ProMax(®) (Planmeca, Helsinki, Finland) and Master 3D(®) (Vatech, Hwaseong, Republic of Korea), have the option of applying an artefact reduction (AR) algorithm. The aim of this study was to determine whether using an AR algorithm in two CBCT machines enhances the accuracy of detecting RFs in endodontically treated teeth. METHODS: 66 roots were collected and decoronated. All roots were treated endodontically using the same technique with gutta-percha and zinc oxide cement. One-half of the roots were randomly selected and fractured using a nail that was tapped gently with a hammer until complete fracture resulted in two root fragments; the two root fragments were glued together with one layer of methyl methacrylate. The roots were placed randomly in eight prepared beef rib fragments. RESULTS: The highest accuracy was obtained when the ProMax was used without AR. The lowest accuracy was obtained with the Master 3D when used with AR. For both machines, accuracy was significantly higher without AR than with AR. Both with and without AR, the ProMax machine was significantly more accurate than the Master 3D machine. The same rank ordering was obtained for both sensitivity and specificity. CONCLUSIONS: For both machines, AR decreased the accuracy of RF detection in endodontically treated teeth. The highest accuracy was obtained when using the ProMax without AR.
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Artefactos , Tomografía Computarizada de Haz Cónico/métodos , Fracturas de los Dientes/diagnóstico por imagen , Raíz del Diente/diagnóstico por imagen , Raíz del Diente/patología , Diente no Vital/diagnóstico por imagen , Algoritmos , Gutapercha , Humanos , Estadísticas no ParamétricasRESUMEN
The prevalence of hepatocellular carcinoma (HCC) was diminished from 60% to 18% at 15 months of age in C3HeB/FeJ male transgenic mice expressing hMGMT in our previous studies. To directly test if the methyltransferase activity is required for diminished tumor prevalence, two separate lines of transgenic mice bearing an enzymatically inactive form of hMGMT were used. In these lines, cysteine 145 was substituted with alanine (C145A). Expression of the hMGMT C145A transgene in liver was demonstrated by Northern blots and Western blots. Immunohistochemistry revealed predominantly nuclear localization of the hMGMT C145A protein. hMGMT C145A transgenic mice were crossed with lacI transgenic mice to assess mutant frequencies in the presence of the mutant protein. Mutant frequencies were similar among livers of lacI × hMGMT C145A bi-transgenic mice and lacI × wild-type (WT) mice. DNA sequence analysis of recovered lacI mutants revealed similar mutation spectra for hMGMT C145A and WT mice. The prevalence of HCC was also similar for the two tested lines of hMGMT C145A mice, 45% and 48% prevalence with median tumor sizes of 11 and 8 mm, and WT mice, 40% prevalence and median tumor size of 10 mm. These results provide evidence that residue C145 in hMGMT is required to reduce the prevalence of HCC in C3HeB/FeJ mice transgenic for hMGMT.
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Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patología , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patología , Hígado/patología , O(6)-Metilguanina-ADN Metiltransferasa/genética , Sustitución de Aminoácidos , Animales , Carcinoma Hepatocelular/enzimología , Activación Enzimática , Humanos , Hígado/enzimología , Hígado/metabolismo , Neoplasias Hepáticas/enzimología , Masculino , Ratones , Ratones Transgénicos , O(6)-Metilguanina-ADN Metiltransferasa/análisis , O(6)-Metilguanina-ADN Metiltransferasa/metabolismo , TransgenesRESUMEN
OBJECTIVE: The objective of this study was to evaluate the potential for a chemically modified Sand blasted, Large grit, Acid etched (SLA) surface, compared with a conventional SLA surface, to enhance implant healing and integration in poorly controlled diabetic patients, a group previously demonstrated to have compromises and delays in implant stabilization during the metabolically active healing period following implant placement. MATERIALS AND METHODS: The study enrolled 24 patients with type 2 diabetes, baseline HbA1c levels between 7.5-11.4%, and a minimum of two posterior mandibular tooth sites at least 4 months following extraction and appropriate for implant placement. Each patient, at a randomly selected site, received an implant with the conventional SLA surface; at the second site, the patient received an implant with the chemically modified SLA (modSLA) surface. Thus, 48 study implants were placed. Implant stability was assessed using Resonance Frequency Analysis (RFA). Readings were taken from the buccal and proximal directions for each implant. Implant stability (ISQ) was assessed at the time of surgical placement (baseline) and 2, 3, 4, 6, 8, 10, 12, and 16 weeks following implant placement. RESULTS: No significant differences in implant stability were observed between conventional SLA implants and modSLA implants, and the time courses of implant stabilization following implant placement were similar for the two implant types. Baseline ISQ and minimum ISQ was slightly higher in subjects with higher HbA1c levels, but were similar during 12-16 weeks following implant placement. Forty-seven (98%) of the 48 implants were determined to be successfully osseointegrated and continued to restoration. CONCLUSION: Implant stabilization was similar for the conventional SLA and chemically modified SLA implants in type 2 diabetic patients with relatively poor glycemic control. Furthermore, this study demonstrated clinically successful implant placement even in poorly controlled diabetic patients.
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Implantación Dental Endoósea/métodos , Implantes Dentales , Diseño de Prótesis Dental , Diabetes Mellitus Tipo 2/complicaciones , Arcada Parcialmente Edéntula/rehabilitación , Grabado Ácido Dental , Adulto , Anciano , Implantación Dental Endoósea/instrumentación , Femenino , Humanos , Masculino , Persona de Mediana Edad , Propiedades de Superficie , Resultado del Tratamiento , Cicatrización de HeridasRESUMEN
Genetically based diseases constitute a major human health burden, and de novo germline mutations represent a source of heritable genetic alterations that can cause such disorders in offspring. The availability of transgenic rodent systems with recoverable, mutation reporter genes has been used to assess the occurrence of spontaneous point mutations in germline cells. Previous studies using the lacI mutation reporter transgenic mouse system showed that the frequency of spontaneous mutations is significantly lower in advanced male germ cells than in somatic cell types from the same individuals. Here we used this same mutation reporter transgene system to show that female germ cells also display a mutation frequency that is lower than that in corresponding somatic cells and similar to that seen in male germ cells, indicating this is a common feature of germ cells in both sexes. In addition, we showed that statistically significant differences in mutation frequencies are evident between germ cells and somatic cells in both sexes as early as mid-fetal stages in the mouse. Finally, a comparison of the mutation frequency in a general population of early type A spermatogonia with that in a population enriched for Thy-1-positive spermatogonia suggests there is heterogeneity among the early spermatogonial population such that a subset of these cells are predestined to form true spermatogonial stem cells. Taken together, these results support the disposable soma theory, which posits that genetic integrity is normally maintained more stringently in the germ line than in the soma and suggests that this is achieved by minimizing the initial occurrence of mutations in early germline cells and their subsequent gametogenic progeny relative to that in somatic cells.
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Regulación del Desarrollo de la Expresión Génica/fisiología , Células Germinativas/fisiología , Animales , Femenino , Genes Reporteros , Represoras Lac/genética , Represoras Lac/metabolismo , Hígado/metabolismo , Masculino , Ratones , Ratones Transgénicos , Mutación , Oocitos/metabolismo , Células de Sertoli/metabolismo , Espermatogonias/metabolismo , Antígenos Thy-1/genética , Antígenos Thy-1/metabolismoRESUMEN
OBJECTIVES: The objectives were to determine whether the images obtained from different cone-beam computerized tomography (CBCT) field of view (FOV) sizes with varying scan time and kilovolt peak using the Picasso Master 3D machine (Vatech, Hwasung, South Korea) differ in contrast-to-noise ratio (CNR). STUDY DESIGN: A phantom was used. Scans were acquired using the same voxel size, 2 scan times (15 and 24 seconds) for 3 different FOV sizes and 5 different kilovolt peaks. The contrast and CNR were calculated for each FOV. RESULTS: The CNRs were similar for the 2 scan times for all 3 FOV sizes. The CNR was lower in the 20 × 19 cm FOV compared with the other 2 FOVs for both scan times. CONCLUSIONS: The CNR does not vary significantly with increasing scan times for all FOV sizes. Smaller FOVs result in enhanced CNR and contrast.
Asunto(s)
Relación Señal-Ruido , Tomografía Computarizada por Rayos X/instrumentación , Humanos , Técnicas In Vitro , Maxilar/diagnóstico por imagen , Fantasmas de ImagenRESUMEN
In this study, numerical course scores of second-year dental students in four successive classes in an oral and maxillofacial pathology course were compared. While the course content and teaching methods were essentially unchanged throughout the four years, two modest departures from the sole use of multiple-choice format questions were made in the assessment of student achievements. The modifications consisted of creating a more challenging examination procedure through the inclusion of un-cued short-answer format questions and the institution of correction-for-guessing scoring on multiple-choice examinations. Academically, the students in the four classes were comparable, as indicated by their respective numerical course score distributions in a prerequisite general pathology course in which the course content was unchanged, and all multiple-choice format questions were used to assess student academic achievements. This four-year study demonstrated that two qualitative changes in the educational environment-utilization of un-cued short-answer questions and correction for guessing scoring of multiple-choice questions-separately resulted in significant improvements in student course scores. Our results support the notion that, without any changes in curricular content or emphasis, combinations of qualitative changes in the assessment procedures alter student behavior and, as a consequence, appreciably improve their academic achievements.
Asunto(s)
Logro , Educación en Odontología , Evaluación Educacional/métodos , Estudiantes de Odontología , Algoritmos , Curriculum , Educación en Odontología/estadística & datos numéricos , Evaluación Educacional/estadística & datos numéricos , Humanos , Aprendizaje , Patología/educación , Patología Bucal/educación , Enseñanza/métodosRESUMEN
Spontaneous mutant frequency in the male germline increases with age, thereby increasing the risk of siring offspring with genetic disorders. In the present study we investigated the effect of age on ionizing radiation-induced male germline mutagenesis. lacI transgenic mice were treated with ionizing radiation at 4-, 15- and 26-month-old, and mutant frequencies were determined for pachytene spermatocytes and round spermatids at 15 days or 49 days after ionizing radiation treatment. Cells collected 15 days after treatment were derivatives of irradiated differentiating spermatogenic cells while cells collected 49 days later were derivatives of spermatogonial stem cells. The results showed that (1) spontaneous mutant frequency increased in spermatogenic cells recovered from nonirradiated old mice (26-months-old), particularly in the round spermatids; (2) mutant frequencies were significantly increased in round spermatids obtained from middle-aged mice (15-months-old) and old age mice (26-months-old) at 15 and 49 days after irradiation compared to the sham-treated old mice; and (3) pachytene spermatocytes obtained from 15- or 26-month-old mice displayed a significantly increased mutant frequency at 15 days post irradiation. This study indicates that age modulates the mutagenic response to ionizing radiation in the male germline.
Asunto(s)
Envejecimiento , Tasa de Mutación , Radiación Ionizante , Espermatocitos/efectos de la radiación , Animales , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones TransgénicosRESUMEN
OBJECTIVES: An algorithm and software to reduce metal artefact has been developed recently and is available in the Picasso Master 3D® (VATECH, Hwaseong, Republic of Korea), which under visual assessment produces better quality images than were obtainable previously. The objective of this in vitro study was to investigate whether the metal artefact reduction (MAR) algorithm of the Picasso Master 3D machine reduced the incidence of metal artefacts and increased the contrast-to-noise ratio (CNR) while maintaining the same gray value when there was no metallic body present within the scanned volume. METHODS: 20 scans with a range of 50-90 kVp were acquired, of which 10 had a metallic bead inserted within a phantom. The images obtained were analysed using public domain software (ImageJ; NIH Image, Bethesda, MD). Area histograms were used to evaluate the mean gray level variation of the epoxy resin-based substitute (ERBS) block and a control area. The CNR was calculated. RESULTS: The MAR algorithm increased the CNR when the metallic bead was present; it enhanced the ERBS gray level independently of the presence of the metallic bead. The image quality also improved as peak tube potential was increased. CONCLUSION: Improved quality of images and regaining of the control gray values of a phantom were achieved when the MAR algorithm was used in the presence of a metallic bead.